How do Self Watering Pots Work? The Incredible Capillary Action Explained (2022)

YouTube video

It’s difficult to remember to water your plants!

Growing plants in containers is especially important for gardeners because…

…they dry out faster and require more care and attention than plants grown in the ground.

Self-watering containers are ideal for gardeners who are too…

…busy to remember to water their plants, people who travel frequently,..

…or anyone who wants to spend more time enjoying their garden rather than caring for it.

They are available in a variety of shapes, sizes, and colors to meet your specific requirements.

But how do self watering pots work?

This is the same question that had been bugging Sabrina’s mind for months.

As an impulsive person, I bought a lot of self-watering pots.

One of the reasons (besides the convenience) is that it’s pretty,..

..and the way it works just fascinates me.

When I bought one too many pots, my husband started to suggest we make one instead.

He said it’s really easy.

However, we weren’t too sure about how do self watering pots work.

Not to worry, here’s where we jump in.

How Do Self Watering Pots Work?

How do self watering pots work
Source: Getty Images

Using self-watering pots is convenient, efficient, and promotes plant health.

However, how do self watering pots work?

These planters and pots use wicking action to deliver water from a built-in reservoir..,

…allowing you to water your plants without constantly monitoring the soil’s…

…moisture level, which is ideal for those who don’t have much time to water.

The self-watering pots work by wicking to bring the soil into contact with the water.

They include a growing bed, potting soil, and water reservoir.

Soil wicks up more water as the plant roots absorb it, ensuring the soil…

…remains at the recommended moisture level.

Self-watering pots, also called sub-irrigation containers, have gained…

…popularity because they are very effective and easy to maintain.

There are many style options available to choose from..,

…from which you can build them yourself using inexpensive, readily available materials.

Self-watering pots have endless design possibilities, but…

…the four basic elements described above always come together…

…to form an elegant houseplant care solution ideal for today’s rushed lifestyles.

The self-watering pot trend has exploded on the scene in recent years…

…because it makes sense once you know how these pots work.

We’ve put together an in-depth guide on how do self watering pots work in…

…the hope that you’ll be inspired to try them.

This is the truth.

Capillary Action (Wicking) Explained

How do self watering pots work 2
Source: Getty Images

Self-watering pots work by drawing water from a surface by…

…using a principle called capillary action.

Capillary action explains how sponges draw liquid, hairs on a paintbrush…

…draw paint, and wicks draw up wax.

Plants, including even the tallest trees, accomplish this feat of overcoming…

…gravity to pull water up from their roots to the top of the plant.

The capillary action of liquids is the result of both intermolecular activities

…of molecules and the attractions between a liquid and a solid that has…

…narrow tubes or small spaces inside it.

Unlike cohesion, which is the attraction between like molecules of a liquid..,

…adhesion occurs between molecules that are unlike one another.

It is similar to how dewdrops cling to a leaf or flower.

In cases where the adhesive force between the liquid and the solid…

…is greater than the cohesive force within the liquid, as is the case…

…when the cracks between solid walls are sufficiently small, the liquid…

…will be propelled within these cracks.

Plants in self-watering pots need to receive a thorough watering…

…of the soil when they are planted.

Then, as they release water from their leaves, they pull water up…

…from the roots through capillary action to replace it.

Capillary action ingests water from the bottom of the reservoir,…

…replacing it with water contained in the soil through the roots,…

…which is also continually supplied from the soil by the roots.

The soil remains consistently moist and not waterlogged with…

…the appropriate potting mixture and wicking mechanism. 

Keep reading…

The Four Basic Elements Of A Self-Watering Pot

How do self watering pots work 3
Source: Getty Images

It doesn’t matter if it’s a single plant or a large container garden..,

…self-watering pots always have the same four components:

Growing Bed

Growing beds hold the potting soil and the plants on higher levels of the container.

Potting Soil

To ensure success with a self-watering pot, you need to use…

…soil that is lightweight and absorbent, whether it is soil or another…

…form of growing medium such as coco coir, perlite, or growstones.

The key is to choose something that consistently pulls water from…

…the ground while also providing plenty of oxygen to the plant roots.

Water Reservoir

A self-watering planter contains a reservoir below the growing bed.

Since you can’t see the reservoir, a viewing window or float will allow…

…you to monitor the water level, eliminating the need for an overflow outlet for indoor planters.

Additionally, the reservoir must be able to be filled, either through…

…a vertical line filling it from above or through an opening on its side.

Providing separate areas for the growing bed and the water reservoir…

…may be done by placing a container in the pot’s bottom, by designing…

…a barrier within the pot, or by using two pots: one for the growing bed and one for the reservoir.

Wicking System

By means of the wicking system, water is delivered from the reservoir…

…to the soil and then to the roots of the plants.

It is either possible to use absorbent materials such as ropes…

…or strips of cloth that are situated with one end in water and…

…the other in soil or you can implement a wicking pot that places…

…the potting mixture directly in contact with the water in the reservoir.

We will examine each of these wicking systems in the following two sections.

Self-Watering Pot Wicks

Using wicks, you can easily move the water from the reservoir to your potting soil.

Wicks can be made from almost any absorbent material, including cotton..,

…wool, felt, nylon, polyurethane, and microfiber.

If your intention is to use the material over a long period of time,…

..however, it is better to use a durable, rot-resistant material such as the…

…fiberglass wick that is used for oil lamps and candle making…

…and that can be found at many gardening suppliers.

A self-watering pot must have wicks that reach the reservoir’s bottom…

….so that they are always in contact with the water, even when the level of the reservoir is low.

You should extend the wicks into the soil rather than place them…

…on the bottom of the growing bed.

To do this, simply hold the top end up as you pour the potting soil into the container.

In order to determine how many wicks you need, you will need to…

…consider factors such as the size of the container, the type of potting soil..,

…type of wicking material, number, and type of plants.

According to the general rule, you need two wicks per plant.

However, you should test the system out with your soil to verify its effectiveness.

If your plants have not been getting adequate water, you may need to make adjustments.

Wicking Pots

Self-watering pots that use wicking systems are often referred to as “wicking pots.”

Wicking pots are self-watering planters with the soil in direct contact…

…with the water, separated only by a permeable barrier.

Most self-watering pots actually function as wicks in and of themselves.

It is this principle that causes some self-watering wicking pots…

…to enable you to convert a regular flowerpot into a self-watering pot…

…by adding a water container to the bottom of the pot that has a perforated…

…top which functions as the growing bed.

Alternatively, you can create a wicking pot by filling a basket with…

…potting soil and extending it down from the growing bed into the reservoir.

Use a container with an opening that allows the soil to contact the water..,

…such as a basket or other container with an opening.

An interior lining made of mesh, window screening, or another thin..,

..permeable fabric ensures soil is kept out.

It is possible to create a self-watering wicking pot by putting gravel…

…or sand in the bottom third of a container that does not have drainage holes..,

…then covering it with permeable cloth until it is completely full.

Shade cloth can be made with anything from old sheets or T-shirts to reusable shopping bags.

Watering shafts can be made with a PVC pipe inserted before filling in the soil.

You will need to cut a hole in the fabric for this.

Sum Up

How do self watering pots work 4
Source: Getty Images

Self-watering planters are a convenient option for plant parents…

…who find it difficult to maintain a consistent watering schedule or who travel frequently.

They are simple to use, eliminate the guesswork in watering,…

…and are suitable for most plant species.


Now that you’ve known more about how do self watering pots work…

It’s time for the action!

Share your experience with self watering pots if you have tried them.

Your story might help a lot of other gardeners!

Frequently Asked Questions Around Self Watering Pots

Are Self Watering Plant Pots Any Good?

While self-watering plant pots are not a new phenomenon,..

…their popularity has recently increased due to their numerous advantages.

These benefits include the ability to combat drought conditions,..

…reduce maintenance requirements, and improve indoor air quality.

Most people rely on rainfall or irrigation systems built into their homes to water their plants.

While these methods are effective for some plants, they may not be sufficient for others.

Self-watering plant pots come in handy here.

These containers use drip irrigation, which directs water from the reservoir…

…inside the pot to the root system of your plants below.

As a result, you don’t have to worry about running out of water…

…or wasting resources; all that’s needed is a steady flow of liquid…

…via your hose hookup (or equivalent).

Do Self Watering Planters Cause Root Rot?

Self-watering planters have been linked to root rot, but this has yet to be proven.

Ideally, you should water your plants with a droplet system…

…or by hand from the top down.

If you need to water your plants more frequently than usual..,

…water them slowly and evenly to avoid over-watering.

Do Self-Watering Pots Have Drainage?

Depending on the design, self-watering pots may or may not have drainage.

Some models have an overflow tube that drains excess water,..

…whereas others simply have a hole in the bottom of the pot that collects it.

In any case, make sure that your pot has enough space for proper…

…drainage so that you don’t end up with flooded landscaping.

How Long Do Self Watering Planters Last?

If you use self-watering planters for plants, keep in mind that they will…

…eventually run out of water.

The length of time required depends on a number of factors..,

…including the type and size of your plant, how frequently you water it,..

…and the climate where you live.

As a general rule, self-watering planters should last between 6 and 12 months,..

…depending on these factors.

More Articles for You

Was this helpful?

Thanks for your feedback!